I have a logic board with 20 pads accessible on it. I know 2 of the 20 pads are UART (TX / RX) and one pad appears to reset the device when connecting a multi meter to it, so I presume that has something to do with JTAG. From what I have read to interface with an SPI bus it requires 4 wires. The 4 wires being,
- MOSI (Master Out Slave In)
- MISO (Master In Slave Out)
- SCLK (Serial Clock)
- SS (Slave Select)
Now with that understanding, how would one determine which of the remaining pads on the device correspond to the 4 wires of the SPI bus? I am assuming that there is a SPI bus interface amongst these 17 remaining pads. How would I determine which four of seventeen remaining pads are associated with the SPI bus? I have access to a logic analyzer if that helps :/